The walls of a home are not necessarily true and flat, but may exhibit inconsistencies in trueness, flatness, or both. When it is desired to install cabinets such as kitchen cabinets in a customer's residence, often a considerable time and effort is spent in conforming the rear of a prefabricated cabinet to an existing wall where the cabinet is to be installed. The present device facilitates cabinet and countertop installation by providing a device that simulates an existing wall so that the rear of a cabinet or countertop can be appropriately modified at factory so as to be complementary to the wall portion at the installation site.